my question is basically this...and is purely hypothetical for the purposes of understanding relative humidity and how itrelates to plant health...say you have a water loving species like thujopsis or metasequoia growing in a very arid climate with relative humidity around 15%...would it be enough to have the plants roots constantly saturated in water or would that be irrelevant since the air is so dry anyway? In other words, is there a point at which the water being lost to transpiration is too great and the amount of water accessible to the roots, no matter how great, is unable to compensate?
Difficult to know. I suspect there are cases where low humidity alone is enough to do that, but there are other issues affecting the situation - if the roots are constantly saturated in water, they'll drown. It is difficult to make sure the test plants have access to enough water but without excluding air from the roots.
That makes sense. But lets say that a mature seedling is in a container whose bottom inch is in a tray of water...leaving out of the equation the potential for root rot, lack of oxygen, etc. Am i correct in assuming that the stomata are the main elements that control water loss, and therefore control drought? And if so, how are the stomata different on a drought tolerant species like Calocedrus from the stomata on a completely drought-vulnerable species like Metasequoia? What are the mechanics of the difference in stomata between these two? And p.s. - thank you in advance for your time!
